Characterization of Staphylococcus aureus isolates from raw milk sources in Victoria, Australia

Background

Highly pathogenic strains of Staphylococcus aureus can cause disease in both humans and animals. In animal species, including ruminants, S. aureus may cause severe or sub-clinical mastitis. Dairy animals with mastitis frequently shed S. aureus into the milk supply which can lead to food poisoning in humans. The aim of this study was to use genotypic and immunological methods to characterize S. aureus isolates from milk-related samples collected from 7 dairy farms across Victoria.

Results

A total of 30 S. aureus isolates were collected from milk and milk filter samples from 3 bovine, 3 caprine and 1 ovine dairy farms across Victoria, Australia. Pulsed Field Gel Electrophoresis (PFGE) identified 11 distinct pulsotypes among isolates; all caprine and ovine isolates shared greater than 80 % similarity regardless of source. Conversely, bovine isolates showed higher diversity. Multi-Locus Sequence Typing (MLST) identified 5 different sequence types (STs) among bovine isolates, associated with human or ruminant lineages. All caprine and ovine isolates were ST133, or a single allele variant of ST133. Two new novel STs were identified among isolates in this study (ST3183 and ST3184). With the exception of these 2 new STs, eBURST analysis predicted all other STs to be founding members of their associated clonal complexes (CCs). Analysis of genetic markers revealed a diverse range of classical staphylococcal enterotoxins (SE) among isolates, with 11 different SEs identified among bovine isolates, compared with just 2 among caprine and ovine isolates. None of the isolates contained mecA, or were resistant to oxacillin. The only antibiotic resistance identified was that of a single isolate resistant to penicillin; this isolate also contained the penicillin resistance gene blaZ. Production of SE was observed at 16 °C and/or 37 °C in milk, however no SE production was detected at 12 °C.

Conclusion

Although this study characterized a limited number of isolates, bovine-associated isolates showed higher genetic diversity than their caprine or ovine counterparts. This was also reflected in a more diverse SE repertoire among bovine isolates. Very little antibiotic resistance was identified among isolates in this study. These results suggest maintaining the milk cold chain will minimise any risk from SE production and highlights the need to prevent temperature abuse.

The social biography of antibiotic use in smallholder dairy farms in India

Background

Antimicrobial resistance (AMR) has been identified as one of the major threats to global health, food security and development today. While there has been considerable attention about the use and misuse of antibiotics amongst human populations in both research and policy environments, there is no definitive estimate of the extent of misuse of antibiotics in the veterinary sector and its contribution to AMR in humans. In this study, we explored the drivers ofirrational usage of verterinary antibiotics in the dairy farming sector in peri-urban India.

Methods and materials

The study was conducted in the peri-urban belts of Ludhiana, Guwahati and Bangalore. A total of 54 interviews (formal and non-formal) were carried out across these three sites. Theme guides were developed to explore different drivers of veterinary antimicrobial use. Data was audio recorded and transcribed. Analysis of the coded data set was carried out using AtlasTi. Version 7. Themes emerged inductively from the set of codes.

Results

Findings were presented based on concept of 'levels of analyses'. Emergent themes were categorised as individual, health systems, and policy level drivers. Low level of knowledge related to antibiotics among farmers, active informal service providers, direct marketing of drugs to the farmers and easily available antibiotics, dispensed without appropriate prescriptions contributed to easy access to antibiotics, and were identified to be the possible drivers contributing to the non-prescribed and self-administered use of antibiotics in the dairy farms.

Conclusions

Smallholding dairy farmers operated within very small margins of profits. The paucity of formal veterinary services at the community level, coupled with easy availability of antibiotics and the need to ensure profits and minimise losses, promoted non-prescribed antibiotic consumption. It is essential that these local drivers of irrational antibiotic use are understood in order to develop interventions and policies that seek to reduce antibiotic misuse.

Mitigating the environmental impacts of milk production via anaerobic digestion of manure: case study of a dairy farm in the Po Valley

This work analyzes the environmental impacts of milk production in an intensive dairy farm situated in the Northern Italy region of the Po Valley. Three manure management scenarios are compared: in Scenario 1 the animal slurry is stored in an open tank and then used as fertilizer. In scenario 2 the manure is processed in an anaerobic digestion plant and the biogas produced is combusted in an internal combustion engine to produce heat (required by the digester) and electricity (exported). Scenario 3 is similar to scenario 2 but the digestate is stored in a gas-tight tank. In scenario 1 the GHG emissions are estimated to be equal to 1.21 kg CO2 eq.kg(-1) Fat and Protein Corrected Milk (FPCM) without allocation of the environmental burden to the by-product meat. With mass allocation, the GHG emissions associated to the milk are reduced to 1.18 kg CO2 eq.kg(-1) FPCM. Using an economic allocation approach the GHG emissions allocated to the milk are 1.13 kg CO2 eq.kg(-1) FPCM. In scenarios 2 and 3, without allocation, the GHG emissions are reduced respectively to 0.92 (-23.7%) and 0.77 (-36.5%) kg CO2 eq.kg(-1) FPCM. If land use change due to soybean production is accounted for, an additional emission of 0.53 kg CO2 eq. should be added, raising the GHG emissions to 1.74, 1.45 and 1.30 kg CO2 eq kg(-1) FPCM in scenarios 1, 2 and 3, respectively. Primary energy from non-renewable resources decreases by 36.2% and 40.6% in scenarios 2 and 3, respectively, with the valorization of the manure in the biogas plant. The other environmental impact mitigated is marine eutrophication that decreases by 8.1% in both scenarios 2 and 3, mostly because of the lower field emissions. There is, however, a trade-off between non-renewable energy and GHG savings and other environmental impacts: acidification (+6.1% and +5.5% in scenarios 2 and 3, respectively), particulate matter emissions (+1.4% and +0.7%) and photochemical ozone formation potential (+41.6% and +42.3%) increase with the adoption of a biogas plant. The cause of the increase is mostly emissions from the CHP engine. These impacts can be tackled by improving biogas combustion technologies to reduce methane and NOx emissions. Freshwater eutrophication slightly increases (+0.8% in both scenarios 2 and 3) because of the additional infrastructures needed. In conclusion, on-farm manure anaerobic digestion with the production of electricity is an effective technology to significantly reduce global environmental impacts of dairy farms (GHG emissions and non-renewable energy consumption), however local impacts may increase as a consequence (especially photochemical ozone formation).

Dairy farm soil presents distinct microbiota and varied prevalence of antibiotic resistance across housing areas

Dairy cattle of different ages experience different living conditions and varied frequency of antibiotic administration that likely influence the distribution of microbiome and resistome in ways that reflect different risks of microbial transmission. To assess the degree of variance in these distributions, fecal and soil samples were collected from six distinct housing areas on commercial dairy farms (n = 7) in Washington State. 16S rRNA gene sequencing indicated that the microbiota differed between different on-farm locations in feces and soil, and in both cases, the microbiota of dairy calves was often distinct from others (P < 0.05). Thirty-two specific antibiotic resistance genes (ARGs) were widely distributed on dairies, of which several clinically relevant ARGs (including cfr, cfrB, and optrA) were identified for the first time at U.S. dairies. Overall, ARGs were observed more frequently in feces and soil from dairy calves and heifers than from hospital, fresh, lactation and dry pens. Droplet-digital PCR demonstrated that the absolute abundance of floR varied greatly across housing areas and this gene was enriched the most in calves and heifers. Furthermore, in an extended analysis with 14 dairies, environmental soils in calf pens had the most antibiotic-resistant Escherichia coli followed by heifer and hospital pens. All soil E. coli isolates (n = 1,905) are resistant to at least 4 different antibiotics, and the PFGE analysis indicated that florfenicol-resistant E. coli is probably shared across geographically-separated farms. This study identified a discrete but predictable distribution of antibiotic resistance genes and organisms, which is important for designing mitigation for higher risk areas on dairy farms.

Overview on GHG emissions of raw milk production and a comparison of milk and cheese carbon footprints of two different systems from northern Spain

Milk production has been estimated to contribute 3-4% of anthropogenic greenhouse gas (GHG) emissions. However, the carbon footprint associated with raw milk can vary, depending on a variety of factors, such as the geographical area, species of cow and production system. In this study, a global overview of research published on the carbon footprint (CF) of raw cow milk is provided. Additionally, two different dairy systems (semi-confinement and pasture-based) have been analysed by life-cycle assessment (LCA) in order to determine their effect on the CF of the milk produced. Inventory data were obtained directly from these facilities, and the main factors involved in milk production were included (co-products, livestock food, water, electricity, diesel, cleaning elements, transport, manure and slurry management, gas emissions to air etc.). In agreement with reviewed literature, it was found that the carbon footprint of milk was basically determined by the cattle feeding system and gas emissions from the cows. The values of milk CF found in the systems under study were within the range for cow milk production worldwide (0.9-4.7 kgCO₂eq kg_FPCM^-1). Specifically, in the semi-confinement and the pasture-based dairy farms, 1.22 and 0.99 kgCO₂eq kg_FPCM^-1 were obtained, respectively. The environmental benefits obtained with the pasture grazing system are not only mainly due to the lower use of purchased fodder but also to the allocation between milk and meat that was found to be a determining methodological factor in CF calculation. Finally, data from the evaluated dairy systems have been employed to analyse the influence of raw milk production on cheese manufacturing. With this aim, the CF of a small-scale cheese factory has also been obtained. The main subsystems involved (raw materials, water, electricity, energy, cleaning products, packaging materials, transport, wastes and gas emissions) were included in the inventory of the cheese factory. CF values were 16.6 and 14.7 kgCO₂eq kg^-1 of cheese for milk produced in semi-confinement and pasture-based systems, respectively. The production of raw milk represented more than 60% of CO₂eq emissions associated with cheese, so the primary production is the critical factor in reducing the GHG emissions due to cheese making.

Distribution of antimicrobial resistance across the overall environment of dairy farms - A case study

The environmental implications of antimicrobial resistance arising from food animal farm practice are still a knowledge gap. This study investigates the fate and transport of antimicrobial resistance genes related to the use of antibiotics on a dairy farm in Michigan. Manure, soil, animal feed, animal drinking water, surface and groundwater samples were taken and the abundance of antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) were subsequently measured using high parallel quantitative PCR targeting 136 genes. The total abundance and detected numbers of ARGs were found to be highest in the stagnant lagoon. Up to 44 ARG subtypes with high abundance were found in drinking water in pen which was very close to those in manure compost. The ARGs pattern clustered by soil depth although they were treated by different manure. ARGs and MGEs were detected in surface and groundwater surrounded by dairy farmlands, with the occurrence of carbapenemase-encoding KPC gene in two waters, which may be due to transport of ARGs through runoff or other sources. Overall, the results of the study suggest high prevalence of ARGs both inside and outside the animal raising area and their potential contribution to environmental ARGs.

The effect of lameness on the environmental performance of milk production by rotational grazing

Dairy production leads to significant environmental impacts and increased production will only be feasible if the environmental performance at farm level permits a sustainable milk supply. Lameness is believed to become more prevalent and severe as herd sizes increase, and can significantly reduce milk output per cow while not influencing other attributes of the production system. The objective of this work was to quantify the effect of lameness on the environmental performance of a typical grazed grass dairy farm and evaluate the theoretical value of sensor-based real-time lameness management. Life cycle assessment was used to compare a typical baseline farm with scenarios assuming increased lameness severity and prevalence. It was found that lameness could increase the farm level global warming potential, acidification potential, eutrophication potential and fossil fuel depletion by 7-9%. As increased herd sizes will increase cow: handler ratio, this result was interpreted to suggest that the use of sensors and information and communication technology for lameness detection could improve management on dairy farms to reduce the adverse impact on environmental performance that is associated with lameness.

Survey of perceptions and attitudes of an international group of veterinarians regarding antibiotic use and resistance on dairy cattle farms

Veterinarians are the main source of information for farmers regarding the responsible use of antibiotics in farm animals and how to reduce the risk of antibiotic resistance. Consequently, understanding how veterinarians perceive their clients' and colleagues' antibiotic use and their own beliefs about the development of antibiotic resistance is essential to determining areas in which antibiotic use practices can be improved to minimize the emergence of antibiotic resistance. An international cross-sectional study was carried out using a questionnaire designed to elucidate perceptions, attitudes, and concerns of dairy veterinarians regarding antibiotic use and the emergence of antibiotic resistance in dairy farming. The questionnaire was initially administered to veterinarians attending the International Bovine Mastitis Conference in Milano, Italy, 2018, followed by veterinarian members of the National Mastitis Council, and all conference registrants. A total of 71 participants from 21 countries participated in the survey, the majority were from the United States and member countries of the European Union. Logistic regression analysis was conducted to identify predictors of veterinarians' level of concern about the development of antibiotic resistance on their clients' farms. Associations were described with odds ratios (ORs) and the associated 95 % confidence intervals (95 % CIs). Free text responses where participants shared their views on the reason for overprescribing antibiotics by veterinarians were analyzed using thematic analysis. Participants perceived that nearly half of their clients overuse or inappropriately use antibiotics, and nearly half of their colleagues overprescribe or inappropriately prescribe antibiotics. After controlling for other factors, the odds of veterinarians being concerned about antibiotic resistance on dairy farms they served decreased by a factor of 0.91 for each additional year of participants' experience working with dairy cattle (OR = 0.91, 95 % CI = 0.84-0.99). Participants concerned about antibiotic resistance on clients' dairy farms were also more likely to consider better adherence to drug labelling as important for reducing farmers' antibiotic use (OR = 6.86, 95 % CI = 1.21-38.93). Thematic analysis revealed four themes surrounding the perceived reasons for veterinarians' overprescribing of antibiotics: (i) knowledge, (ii) attitudes, (iii) barriers, and (iv) rules and regulations. The study findings will aid in the development of strategies to improve antibiotic use in dairy farming and educational initiatives looking to enhance the communication between veterinarians and farmers about judicious use of antibiotics.

On-farm soil resistome is modified after treating dairy calves with the antibiotic florfenicol

We determined the immediate impact of exposure to antibiotic-treated animals on housing soil microbiome and resistome. Fecal (n = 36) and soil (n = 108) samples from dairy calves (n = 6) treated with and without florfenicol over 30 days were collected. There were temporary changes in the gut microbiome of antibiotic-treated calves as measured by Shannon diversity (16S rRNA gene sequencing; P = 0.03), but not in the housing soil microbiome (P > 0.05). Droplet-digital PCR demonstrated that floR gene increased by 1-log in soil exposed to treated animals (P < 0.001), but it remained relatively stable in the control soil whereby calves were not treated with antibiotic. Resistome in exposed soil was largely modified (P = 0.004) with the overall prevalence of antimicrobial resistance genes (ARGs) significantly elevated (3.8-fold increase by day 10; P = 0.01). In addition to florfenicol, enriched ARGs collectively conferring resistance to tetracyclines, aminoglycosides, sulfonamides, elfamycins, macrolides-lincosamides-streptrogramin A/B, and beta-lactams. Quantitative PCR validated that ARGs including str and tetG in soil exposed to florfenicol-treated calves had gradually increased fold-change difference relative to the control soil over time. Moreover, a greater diversity of transferrable ARGs was observed in exposed soil and these were associated with a greater diversity of bacterial species. Evaluation of on-farm effects to soil in situ after exposure to antibiotic-treated animals can help design effective managements to mitigate antibiotic resistance in food-animal production.

Anaerobic digestion and milking frequency as mitigation strategies of the environmental burden in the milk production system

The aim of the study was to assess, through a cradle to farm gate Life Cycle Assessment, different mitigation strategies of the potential environmental impacts of milk production at farm level. The environmental performances of a conventional intensive dairy farm in Northern Italy (baseline scenario) were compared with the results obtained: from the introduction of the third daily milking and from the adoption of anaerobic digestion (AD) of animal slurry in a consortium AD plant. The AD plant, fed only with animal slurries coming also from nearby farms. Key parameters concerning on-farm activities (forage production, energy consumptions, agricultural machines maintenance, manure and livestock management), off-farm activities (production of fertilizers, pesticides, bedding materials, purchased forages, purchased concentrate feed, replacement animals, agricultural machines manufacturing, electricity, fuel) and transportation were considered. The functional unit was 1kg fat and protein corrected milk (FPCM) leaving the farm gate. The selected environmental impact categories were: global warming potential, acidification, eutrophication, photochemical oxidation and non-renewable energy use. The production of 1kg of FPCM caused, in the baseline scenario, the following environmental impact potentials: global warming potential 1.12kg CO2 eq; acidification 15.5g SO2 eq; eutrophication 5.62g PO4(3-) eq; photochemical oxidation 0.87g C2H4 eq/kg FPCM; energy use 4.66MJeq. The increase of milking frequency improved environmental performances for all impact categories in comparison with the baseline scenario; in particular acidification and eutrophication potentials showed the largest reductions (-11 and -12%, respectively). In anaerobic digestion scenario, compared to the baseline one, most of the impact potentials were strongly reduced. In particular the most important advantages were in terms of acidification (-29%), global warming (-22%) and eutrophication potential (-18%). The AD of cow slurry is confirmed as an effective strategy to mitigate the environmental impact of milk production at farm level.

A multicomponent ergonomic intervention involving individual and organisational changes for improving musculoskeletal outcomes and exposure risks among dairy workers

A field intervention study was implemented to evaluate the effects of individual (physical exercise programme and worker ergonomics training) and organisational changes (optimising work-rest schedule and revised task procedure) on musculoskeletal outcomes and their exposure risks among milking workers in a dairy plant. A questionnaire survey (including the Cornell Musculoskeletal Discomfort Questionnaire [CMDQ]) and direct observations of working postures by using the Quick Exposure Check (QEC) method were used at baseline and 12-month follow-up. Shoulder, lower back and neck discomfort were found to be the most common problems. The results showed significant improvements in the frequency (neck, shoulder, lower back, forearm and knee symptoms), severity (shoulder, lower back and knee symptoms) and interference with work (particularly due to lower back symptoms) as well as in the exposure risks to musculoskeletal problems (using the QEC method) after the intervention. The findings support the effectiveness of implemented multiple component intervention for improving musculoskeletal health and exposure risks in the studied occupational group.

Characterization of Escherichia coli and Salmonella from Victoria, Australia, Dairy Farm Environments

Safe dairy food production starts at the farm level, with the presence of pathogens on farms potentially impacting the downstream food supply. Studies often commence with looking for pathogens in fecal material of farm animals, predominantly cows; however, pathogens may arise from other on-farm sources. In Australia, few studies have looked at the broader farm environment, particularly in relation to Escherichia coli and Salmonella. The present study characterized the genetic similarity of these pathogens from bovine, ovine, and caprine dairy farm environments and related this to the stx₁, stx₂, eae, or ehx virulence markers in E. coli and antibiotic resistance in Salmonella. E. coli isolates with indistinguishable genetic profiles and at least one of the virulence factors were found in multiple samples on the farms, although profiles were unique to each farm. E. coli O26 with stx₁ from one bovine farm had a different fingerprint type than all of the other E. coli O26 isolates, which lacked the Shiga toxin genes. They were from a separate bovine farm and were themselves closely related. No antibiotic resistance was detected among Salmonella isolates to the 17 antibiotics tested. Three Salmonella serotypes were identified: Orion, Infantis, and Zanzibar. The published PCR serotyping method used misidentified Salmonella Zanzibar as Salmonella Javiana, which was revealed after conventional antisera-based serotyping; this illustrates the need for caution when using PCR techniques for Salmonella serotype identification. Of the three serotypes, Salmonella Orion was most prevalent and was potentially resident on the farm. This article describes the previously unreported genetic diversity of potentially pathogenic E. coli and Salmonella serotypes from the farm environments of three dairy animal species in Victoria, Australia.

Community, system and policy level drivers of bovine tuberculosis in smallholder periurban dairy farms in India: a qualitative enquiry

BACKGROUND

Rapid urbanization has led to expansion of peri-urban fringes, where intensive, industry-style livestock rearing has led to emerging vulnerabilities at the human-animal-environment interface. This study was undertaken to understand the health system and farm-level factors that influenced the risk of transmission of bovine Tuberculosis (bTB) in animals and humans in peri-urban smallholder dairy farms of India.

METHODS

Thematic guides were developing through literature review and expert consultation. In-depth interviews were conducted till attainment of saturation. Identification of core themes was followed by etiological enquiry and generation of a conceptual model.

RESULTS

Veterinarians were consulted as a last resort after home-remedies and quacks had failed. Damage control measures, especially with respect to- selling or abandoning sick animals, added to the risk of disease transmission. Although civic authorities believed in the adequacy of a functioning laboratory network, end users were aggrieved at the lack of services. Despite the presence of extension services, knowledge and awareness was limited, promoting risky behaviour. The absence of cogent policies in dealing with bTB was a significant barrier. Stakeholders did not consider bTB to be a major concern. It is possible that they underestimate the problem.

CONCLUSION

The current study helps to identify gaps which need to be addressed through collaborative research, and OneHealth interventions to build community awareness.

Metal speciation and potential bioavailability changes during discharge and neutralisation of acidic drainage water

The discharge of acid drainage from the farm irrigation areas to the Murray River in South Australia represents a potential risk to water quality. The drainage waters have low pH (2.9-5.7), high acidity (up to 1190 mg L(-1) CaCO3), high dissolved organic carbon (10-40 mg L(-1)), and high dissolved Al, Co, Ni and Zn (up to 55, 1.25, 1.30 and 1.10 mg L(-1), respectively) that represent the greatest concern relative to water quality guidelines (WQGs). To provide information on bioavailability, changes in metal speciation were assessed during mixing experiments using filtration (colloidal metals) and Chelex-lability (free metal ions and weak inorganic metal complexes) methods. Following mixing of drainage and river water, much of the dissolved aluminium and iron precipitated. The concentrations of other metals generally decreased conservatively in proportion to the dilution initially, but longer mixing periods caused increased precipitation or adsorption to particulate phases. Dissolved Co, Mn and Zn were typically 95-100% present in Chelex-labile forms, whereas 40-70% of the dissolved nickel was Chelex-labile and the remaining non-labile fraction of dissolved nickel was associated with fine colloids or complexed by organic ligands that increased with time. Despite the different kinetics of precipitation, adsorption and complexation reactions, the dissolved metal concentrations were generally highly correlated for the pooled data sets, indicating that the major factors controlling the concentrations were similar for each metal (pH, dilution, and time following mixing). For dilutions of the drainage waters of less than 1% with Murray River water, none of the metals should exceed the WQGs. However, the high concentrations of metals associated with fine precipitates within the receiving waters may represent a risk to some aquatic organisms.

A life cycle assessment study of dairy farms in northern Germany: The influence of performance parameters on environmental efficiency

Recently, consumers concerns towards an environmental friendly food production are growing. The dairy sector contributes to the production of important greenhouse gases such as methane. The life cycle assessment (LCA) method enables to quantify the emissions and the use of resources throughout the entire life cycle of a product. The aim of the current study was to investigate the influence of performance parameters on the level of important environmental impacts (global warming potential (GWP), freshwater eutrophication (FE), terrestrial acidification (TA) and agricultural land occupation (ALO)) associated with milk production. Therein, the environmental impacts were analyzed using LCA considering two separate datasets (total, continuous) from Northern German farms throughout the years 2004-2013. Therefore, the performance parameters determining the level of environmental impacts were identified using the partial least square method. Thereby, a differentiated analysis among regions with various soil characteristics (Heath, Hill, Marsh) was conducted additionally. Further, linear mixed models were applied to each of the environmental impact categories. Energy-corrected milk yield (ECM), ECM from roughage, feed efficiency and the use of concentrates were identified as the most important determinants of environmental impacts. In general, an increase in productivity, especially an increase in ECM per cow and an increase in the amount of ECM produced per area of agricultural land accompanied with an improvement in environmental efficiency. The type of feed used had the major impact on the level of environmental impacts, whereby both concentrates and roughage had disadvantages. These results were in line with previous studies. Although, this study provides additional information relating the most important determinants of different environmental impacts, including a differentiated consideration of the relationship between performance parameters and environmental efficiency among regions. Further analyses on specific soil characteristics and their impact on environmental efficiency are recommended. In line with the concept of eco-efficiency, useful mitigation strategies in practice need to be applied depending on individual framework conditions.

The carbon footprint of integrated milk production and renewable energy systems - A case study

Dairy farms have been widely acknowledged as a source of greenhouse gas (GHG) emissions. The need for a more environmentally friendly milk production system will likely be important going forward. Whereas methane (CH₄) enteric emissions can only be reduced to a limited extent, CH₄ manure emissions can be reduced by implementing mitigation strategies, such as the use of an anaerobic digestion (AD). Furthermore, implementing a photovoltaic (PV) electricity generation system could mitigate the fossil fuels used to cover the electrical needs of farms. In the present study to detect the main environmental hotspots of milk production, a Life Cycle Assessment was adopted to build the Life Cycle Inventory according to ISO 14040 and 14044 in a conventional dairy farm (1368 animals) provided by AD and PV systems. The Intergovernmental Panel on Climate Change tiered approach was adopted to associate the level of emission with each item in the life cycle inventory. The functional unit refers to 1kg of fat-and-protein-corrected-milk (FPCM). In addition to milk products, other important co-products need to be considered: meat and renewable energy production from AD and PV systems. A physical allocation was applied to attribute GHG emissions among milk and meat products. Renewable energy production from AD and PV systems was considered, discounting carbon credits due to lower CH₄ manure emissions and to the minor exploitation of fossil energy. The CF of this farm scenario was 1.11kg CO₂eq/kg FPCM. The inclusion of AD allowed for the reduction of GHG emissions from milk production by 0.26kg CO₂eq/kg FPCM. The PV system contribution was negligible due to the small dimensions of the technology. The results obtained in this study confirm that integrating milk production with other co-products, originated from more efficient manure management, is a successful strategy to mitigate the environmental impact of dairy production.

Cow hair allergen concentrations in dairy farms with automatic and conventional milking systems: From stable to bedroom

Bovine hair and dander are considered to be a notable risk factor for sensitization and allergic symptoms in occupationally exposed cattle farmers due to various IgE binding proteins. Farmers are suspected not only to be exposed during their work inside the stables but also inside their homes as allergens could be transferred via hair and clothes resulting in continued bovine allergen exposure in private areas. In recent years a new sensitive sandwich ELISA (enzyme linked immunosorbent assay) test has been developed to measure the cow hair allergen (CHA) concentration in dust. The aim of the present study was to determine the CHA concentration in airborne and settled dust samples in stables and private rooms of dairy cattle farms with automatic milking systems (AM) and conventional milking systems (CM), also with respect to questionnaire data on farming characteristics. For this purpose different sampling techniques were applied, and results and practicability of the techniques were compared. Dust sampling was performed in the stable, computer room (only AM), changing room, living room and bedroom (mattress) of 12 dairy farms with automatic milking systems (AM group) and eight dairy farms with conventional milking systems (CM group). Altogether, 90 samples were taken by ALK filter dust collectors from all locations, while 32 samples were collected by an ion charging device (ICD) and 24 samples by an electronic dust fall collector (EDC) in computer rooms (AM) and/or changing and living rooms (not stables). The dust samples were extracted and analyzed for CHA content with a sandwich ELISA. At all investigated locations, CHA concentrations were above the limit of detection (LOD) of 0.1 ng/ml dust extract. The median CHA concentrations in dust collected by ALK filters ranged from 63 to 7154 μg/g dust in AM farms and from 121 to 5627 μg/g dust in CM farms with a steep concentration gradient from stables to bedrooms. ICD sampling revealed median CHA contents of 112 μg/g airborne dust in the computer rooms of the AM farms and median CHA loads of 5.6 μg/g (AM farms) and 19.8 μg/g (CM farms) in the living rooms. Passive dust sampling by EDC was performed only at two locations in the AM group resulting in median CHA values of 116 μg/m(2) (computer room) and 55.0 μg/m(2) (changing room). Except for the stable samples the median CHA load was lower in AM farms compared to CM farms. The CHA contents of ALK filter samples were significantly correlated in most locations. Differences between the farming types were not significant. Although allergen transfer to the private area of the farmers has been found and results from several locations were correlated, differences in CHA concentrations were not significant with respect to questionnaire data such as the wearing of stable clothes in living room, free access of pets to stable and home, frequency of hair washing. All sampling techniques seem to being practicable for simple and effective CHA measurement.

A cross-sectional survey and follow up study on major dairy health problems in large and small scale urban farms in Mekelle, Tigray, Ethiopia

Objective

This study was conducted with the objective of estimating the incidence of major dairy health problems in the area.

Result

From a cross-sectional survey (n = 475) and follow up study (n = 68), an overall incidence of 43.00 and 29.02% was reported respectively. This study showed biting fly (9.51%), respiratory problems (7.80%), mastitis (5.13%), actinomycosis (5.12%), dystocia (4.42%), endoparasites (3.81%), retention fetal membrane (3.63%), tick infestation (2.91%), lameness (2.94%), vaginal and uterine prolepses (2.51%), skin related problem (1.70%) and abortion (1.70%) were the main dairy health problems identified. In addition, the follow up study revealed; retention fetal membrane (5.91%), tick infestation (5.91%), respiratory problem (2.91%), mastitis (2.94%), endoparasites (2.94%), lameness (2.94%), dystocia (2.94%), actinomycosis (1.53%) and skin related problems (1.53%). The incidence of dairy reproductive problems showed statistically significant variation among local and cross breeds (P < 0.05). Incidence of infectious diseases among dairy cows managed under intensive and semi-intensive management systems showed a significant difference (P < 0.05). Moreover, incidence of physical injury was also showed a significant difference among animal breeds and management system (P < 0.05). However, reproductive problems among management system and infectious diseases among breeds showed a significant difference (P > 0.05). Overall, this study showed dairy animals are exposed to various type of diseases.

Bacteriological study of calf colisepticemia in Alage Dairy Farm, Southern Ethiopia

OBJECTIVE

This study was designed to estimate the prevalence of E. coli which is the main cause of colisepticemia and the potential risk factors associated with the disease. A total of 74 calves less than 6 months age were selected for this study. For isolation and identification of E. coli, bacterial culture and biochemical tests were used.

RESULT

Out of 74 calves selected for this study, 6 (8.11%) were positive for septicemic E. coli. Higher prevalence of 5 (8.93%) was recorded in Holstein Friesian breed than Boran breed 1 (5.56%). However, breed showed no significant difference on E. coli infections (P > 0.05). Higher prevalence of E. coli revealed below age of 30 days (17.39%) than calves aged between 30 and 90 days (8.33%) and above 90 days (0.00%). However, statistical association showed no difference (P > 0.05). Parity showed a significant difference in prevalence of E. coli (P < 0.05) in which infection increased with number of parity. Sex of the animal showed no association with infection of the calves (P > 0.05). Diarrheic calves showed higher prevalence (33.3%) than non-diarrheic calves (4.62%) with strong statistical association (P < 0.05). The present study showed a high prevalence of septicemic E. coli in the farm and intervention is strongly recommended.

Microbial quality of raw cow milk and its predictors along the dairy value chain in Southwest Ethiopia

Raw milk may contain pathogenic microorganism that can seriously affect the health of consumers. In Southwest Ethiopia, raw cow milk is consumed more than the processed products, but its microbiological quality and its predictors are not studied well. The aim of this study was to determine the microbial quality of raw cow milk and its predictors along the dairy value chain in Southwest Ethiopia. A total of 150 milk and 300 environmental samples were collected randomly from dairy farms, milk distribution centers, and retailer outlets for microbiological analysis using standard protocols. One milk handler from each milk production or distribution stage was also interviewed to assess the knowledge, attitude, and practices regarding milk handling. Descriptive statistics and multiple linear regression models were used to summarize the data and to identify predictors of milk microbial quality, respectively. As the milk transported from dairy farm to milk retailer outlet, the mean total bacterial count has increased from 5.0 ± 0.3 to 7.2 ± 0.1 log CFU/ml respectively. The mean coliform count of the milk sample was 4.4 ± 0.4 log CFU/ml at the dairy farm and 7.0 ± 0.2 log CFU/ml at milk selling points, indicating the deterioration of milk quality along the dairy value chain. All of the analyzed water samples were positive for fecal coliform bacteria. The highest coliform bacteria were reported from milk storage equipment found at milk retailer outlet with the count of 4.8 ± 0.5 log CFU/ml. Educational status and attitude of milk handlers and the quality of water used to wash milk equipment and hands of milk handlers were the major factors affecting the microbial quality of raw cow milk. The findings of this study revealed that the microbial quality of raw milk in the study area was poor. Hence, improving the attitude and educational status of milk handlers, and the quality of water is an important step to enhance milk quality and consequently to prevent milk borne diseases.

Bacterial hazard identification and exposure assessment of raw milk consumption in Jimma zone, South West Ethiopia

BACKGROUND

Raw milk may contain pathogenic microorganism that can sometimes fatally affect the health of consumers. However, risks related to raw milk consumption in Southwest Ethiopia are not well studied. The aim of this study was to evaluate the presence of five target pathogenic bacteria including Escherichia coli O157:H7, Salmonella enterica Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Campylobacter jejuni in raw milk and to assess exposure associated with the consumption of raw milk.

METHOD

A cross-sectional study was carried out between November 2019 and June 2020 to in Jimma zone, Southwest Ethiopia. Laboratory analysis was conducted on milk samples collected from Seven Woreda towns, including, Agaro, Yebu, Sekoru, Serbo, Shebe, Seka, Sheki and Jimma town administration. Semi-structured interview questions were administered to collect data on the amount and frequency of consumption. Descriptive statistics were used to summarize laboratory results and questionnaire survey data.

RESULT

Among 150 total raw milk samples, about 61.3% were found contaminated by one or more types of pathogens along the dairy value chain. The highest and the least bacterial counts recorded were 4.88 log10cfu/ml and 3.45 log10cfu/ml from E. coli and L. monocytogenes respectively. The mean concentrations of pathogens demonstrated significant statistical difference (p < 0.05) using 95% confidence interval where the prevalence percentage of isolates increased as the milk was transported from farms to the retail outlets. Except for C. jejuni; all other pathogens were detected in the range of unsatisfactory level of milk microbiological quality along the chain. The estimated mean annual risk of acquiring intoxication of E. coli across retailer outlets is 100% whereas salmonellosis, S. aureus intoxication, and listeriosis are 84%, 65% and 63% respectively.

CONCLUSION

The study highlights the significant health risks associated with the consumption of raw milk due to its unacceptable microbiological quality. The traditional production and consumption patterns of raw milk are the primary reasons for the high annual probability of infection. Therefore, regular monitoring and implementation of hazard identification and critical control point principles are necessary from raw milk production to retail points to ensure the safety of consumers.

Evaluating the use of an Unmanned Aerial Vehicle (UAV)-based active AirCore system to quantify methane emissions from dairy cows

Enteric fermentation and manure methane emissions from livestock are major anthropogenic greenhouse gas emissions. In general, direct measurements of farm-scale methane emissions are scarce due to the source complexity and the limitations of existing atmospheric sampling methods. Using an innovative UAV-based active AirCore system, we have performed accurate atmospheric measurements of CH₄ mole fractions downwind of a dairy cow farm in the Netherlands on four individual days during the period from March 2017 to March 2019. The total CH₄ emission rates from the farm were determined using the UAV-based mass balance approach to be 1.1-2.4 g/s. After subtracting estimated emission factors of manure onsite, we derived the enteric emission factors to be 0.20-0.51 kgCH₄/AU/d (1 AU = 500 kg animal weight) of dairy cows. We show that the uncertainties of the estimates were dominated by the variabilities in the wind speed and the angle between the wind and the flight transect. Furthermore, nonsimultaneous sampling in the vertical direction of the plume is one of the main limiting factors to achieving accurate estimate of the CH₄ emissions from the farm. In addition, a N₂O tracer release experiment at the farm was performed when both a UAV and a mobile van were present to simultaneously sample the N₂O tracer and the CH₄ plumes from the farm, improving the source quantification with a correction factor of 1.04 and 1.22 for the inverse Gaussian approach and for the mass balance approach, respectively. The UAV-based active AirCore system is capable of providing useful estimates of CH₄ emissions from dairy cow farms. The uncertainties of the estimates can be improved when combined with accurate measurements of local wind speed and direction or when combined with a tracer approach.

Phosphorus feeding practices, barriers to and motivators for minimising phosphorus feeding to dairy cows in diverse dairy farming systems

Minimising phosphorus (P) feeding to dairy cows can reduce feed costs and minimise water pollution without impairing animal performance. This study aimed to determine current P feeding practices and identify the barriers to and motivators for minimising P feeding on dairy farms, using Great Britain (GB) dairy farming as an example of diverse systems. Farmers (n = 139) and feed advisers (n = 31) were involved simultaneously in independent questionnaire surveys on P feeding in dairy farms. Data on the herd size, milk yield and concentrate fed were analysed using ANOVA to investigate the effect of farm classification, region, and feed professional advice. Chi-square tests were used to investigate associations between farm characteristics and implemented P feeding and management practices. Most farmers (72%) did not know the P concentration in their lactating cow's diet and did not commonly adopt precision P feeding practices, indicating that cows might have been offered dietary P in excess of recommended P requirement. Farmers' tendency to feed P in excess of recommendations increased with herd size, but so did their awareness of P pollution issues and likeliness of testing manure P. However, 68% of farmers did not analyse manure P, indicating that mineral P fertiliser application rates were not adjusted accordingly, highlighting the risk of P being applied beyond crops' requirement. Almost all farmers (96%) were willing to lower dietary P concentration but the uncertainty of P availability in feed ingredients (30%) and concerns over reduced cow fertility (22%) were primary barriers. The willingness to reduce dietary P concentrations was driven by the prospect of reducing environmental damage (28%) and feed costs (27%) and advice from their feed professionals (25%). Most farmers (70%) relied on a feed professional, and these farmers had a higher tendency to analyse their forage P. However, farmers of pasture-based systems relied less on feed professionals. Both farmers (73%) and feed advisers (68%) were unsatisfied with the amount of training on P management available. Therefore, the training on P management needs to be more available and the influence that feed professionals have over P feeding should be better utilised. Study findings demonstrate the importance of considering type of dairy farming systems when developing precision P feeding strategies and highlight the increasing importance of feed professionals in minimising P feeding.

Tracking high-risk β-lactamase gene (bla gene) transfers in two Chinese intensive dairy farms

Extended-spectrum β-lactam antibiotics are critically important antibiotics for humans, but their use in food-animals poses a potential threat for public health. This paper addressed the occurrence of high-risk β-lactamase genes (bla genes) in intensive dairy farms, and assessed the effects of different waste treatment technologies at dairies on the propagation and dissemination of bla genes. Results showed that ESBL genes (bla_TEM-1, bla_OXA-1), ampC β-lactamase genes (bla_ampC) and carbapenemase genes (bla_GES-1, bla_NDM) were prevalent in dairy cow waste, and even prevailed through each processing stage of solid manure and dairy wastewater. Significant levels of bla genes were present in the final lagoon (from 10⁴ to 10⁶ copies/mL, representing from 10% to 151%, of raw influent levels), raising the possibility of dissemination to the receiving environment. This concern was validated by the investigation on farmland that had long-term undergone wastewater irrigation, where causing an increase in bla gene levels in soils (approximately 1-3 orders of magnitude). More troublesomely, considerable levels of certain bla genes were still observed in the bedding material (up to 10⁵ and 10⁷ copies/g), which would directly threaten the dairy cow health. Otherwise, correlation analysis showed that both bacterial community and environmental factors played important roles in the bla genes abundances in dairy farms. This study demonstrated the prevalence of high-risk bla genes in dairy farms, and also underscored that dairy waste was a non-ignored great source of multidrug resistance for their surroundings.

Complete chromosome and plasmid sequences of Staphylococcus aureus strain JDFM SA01, isolated from a milk filter in Korean dairy farm

Staphylococcus aureus is a significant pathogen that can source a variety of illness worldwide. In this announcement, we report here the complete genome sequence of S. aureus strain JDFM SA01, isolated from a milk filter collected from Korean dairy farm. The final complete genome assembly consists of one circular chromosome (2,748,925 bp) with an overall GC content of 32.9% and one circular plasmid sequence (24,655 bp) with a GC content of 28.7%.